<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<script>
			var year = prompt("请你输入年份");
			var isrunnian = year % 4 == 0 && year % 100 != 0 || year % 400 == 0;
			for(var i = 1; i <= 12; i++) {
				if(i == 4 || i == 6 || i == 9 || i == 11) {
					document.write(i + "月有30天<br />")
				} else if(i == 2) {
					if(isrunnian) {
						document.write(i + "月有29天<br />")
					} else {
						document.write(i + "月有28天<br />")
					}
				} else {
					document.write(i + "月有31天<br />")
				}

			}
		</script>
	</body>

</html>